1. Field of the Invention
The present invention relates to an image generating system and an image generation method.
2. Description of the Related Arts
Conventionally, there has been an image generating system which can give a feeling of virtual reality, by means of converting an object observed from a virtual viewpoint, in a three-dimensional virtual space, into image data having two-dimensional coordinates, and displaying the data on a display unit.
When such an image generating system is applied as a game machine, with which the player can enjoy playing, for example, a racing game, the player can drive a racing car, which is the object, and run throughout the space. Further, the player can take part in a virtual reality car racing against a racing car driven by another player.
At this time, it is important to give a feeling of further sophisticated virtual reality to the player, in order to encourage the player to keep his interest in playing games with a game machine, thereby forcing the player to select his preferable program to execute the game.
One of the factors for giving a feeling of even more sophisticated virtual reality to the player is to reflect the environment surrounding the object into the image of the object (in the above example, a racing car) placed in a three-dimensional virtual space. In other words, the environment surrounding the object is superimposed on the image of the object.
As a technology for this purpose, there is the invention, for example, as disclosed in Japanese Patent Application Laid-Open (kokai) No. 2001-70633.
Such an invention as disclosed in Patent Laid-Open is to map the environmental texture, that should be visible in the upward direction viewed from the object (for example, a racing car), on the object from the upward direction of the object, not depending on the position or rotational angle of the virtual camera. And, the environmental texture is pre-rendered to the texture memory, like the texture of the object itself. By this pre-rendering, reflection of light emitting sources, etc. can be expressed naturally.
As described above, in the invention disclosed in Japanese Patent Application Laid-Open (kokai) No. 2001-70633, the texture of the surrounding environment to be reflected into the image of the object is pre-rendered to the memory.
Therefore, it is difficult to promptly reflect a change with time to the texture to be reflected, in accordance with the time change of the object, which is subject to reflection (for example, a car) and reflecting things (all environmental things surrounding the car, such as light emitting sources, landscape, etc.) (change in the environmental image with the move of the car).
Furthermore, for example, in a racing game, etc., the car appearing on the screen is desirably able to give a feeling of reality in the expression of its painted body, including brightness and luster, when reflection is made on the car.